A novel Gram-stain-negative, facultatively anaerobic, non-motile and short rod-shaped bacterium, strain KBL009(T), was isolated from the larval gut of Hermetia illucens. Strain KBL009(T) grew optimally at 37 °C, at pH 6.0 and with 1-2 % (w/v) NaCl. The 16S rRNA gene sequence of strain KBL009(T) showed 97.6 % similarity to that of Paenalcaligenes hominis CCUG 53761A(T) indicating its classification with the genus Paenalcaligenes. The major fatty acids were cyclo-C17 : 0, C16 : 0 and summed feature 2 (comprising C14 : 0 3-OH/iso-C16 : 1). The respiratory quinones were ubiquinone-8 (Q-8), predominating, and a minor amount of Q-7. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, one unknown aminolipid and five unknown polar lipids. The polyamine pattern contained predominantly putrescine and relatively high amounts of spermidine. The betaproteobacterial-specific 2-hydroxyputrescine could only be detected in trace amounts. The G+C content of genomic DNA was 56.1 mol%. Results from DNA-DNA hybridization with P. hominis KCTC 23583(T) unambiguously demonstrated that strain KBL009(T) represents a novel species in the genus Paenalcaligenes. Based on phenotypic, genotypic and phylogenetic characterization, the novel species Paenalcaligenes hermetiae sp. nov. is proposed. The type strain is KBL009(T) ( = KACC 16840(T) = JCM 18423(T)). An emended description of the genus Paenalcaligenes is also provided.